Precision pipe advancement mechanism for bending machine



F. H. KELLEY Nov. 22, 1960 PRECISION PIPE ADVANCEMENT MECHANISM FOR BENDING MACHINE Filed Aug. 5, 1959 3 Sheets-Sheet 1- y W Rh N N m m N a N MM 4 Nov, 22, 1960 KELLEY 2,961,090

PRECISION PIPE ADVANCEMENT MECHANISM FOR BENDING MACHINE Filed Aug. 5, 1959 3 Sheets-Sheet 2 .464 INVENTOR. a? 99; 220 w A TTORNEV F. H. KELLEY Nov. 22, 1960 PRECISION PIPE ADVANCEMENT MECHANISM FOR BENDING MACHINE Filed Aug. 5, 1959 3 Sheets-Sheet 3 rromgzzs.

United States Patent 0 PRECISION PIPE ADVANCEMENT MECHANISM FOR BENDING MACHINE Forrest H. Kelley, Rte. 1, Osceola, Mo.

Filed Aug. 5, 1959, Ser. No. 831,898

10 Claims. (Cl. 226-135) This invention relates to a machine for bending pipes, conduits, bars and similar tubular elements, the primary object being to provide precision mechanism for advancing such elements through suitable bending apparatus and constituting an improvement over the mechanism disclosed in my application Serial No. 718,836, filed March 3, 1958, entitled Precision Pipe Advancement Mechanism for Bending Machine, and of which this application is a continuation-in-part.

Various types of pipe bending machines have been previously provided but the same have not been entirely satisfactory because they were either too complicated in design and operation or incapable of accurately advancing the pipe through the bending apparatus so that the desired degree of bend was obtained. The present mechanism has particular utility in the field of electrical conduits wherein it is necessary to bend conduits which are supplied in standard lengths, it being necessary to not only bend such conduits at predetermined angles but also in a manner so that the outer end of the bent portion terminates in predetermined spaced relationship to the unbent length of the pipe. As referred to above, electrical conduits are commercially supplied in standard lengths such as ten feet and during construction operations, it is necessary to bend the conduits into specified configurations for meeting the specifications of the building being constructed. Conduits of the type described. are often several inches in diameter and a problem is presented in attempting to bend such conduits without forming of dimples or eggs in the surface thereof.

The prior pipe bending machines have generally utilized a reciprocable shoe adapted to be shifted toward a pair of spaced structures supporting a pipe so that as the shoe is moved toward the structures, the pipe is bent therebetween. However, because of the size of the conduit, in order to bend the conduit to a required degree, it is ordinarily necessary to direct the shoe against the pipe at a plurality of spaced intervals along the length thereofso that the angle of bend at each shot is relatively small. It has been determined that for relatively large electrical conduits, the movement of the pipe at each shot must be below one and one-half inch to prevent forrnation of the dimples and eggs described above.

Heretofore the standard procedure in bending of electrical conduits has been to determine the degree of bend desired and the radius of the bend so that the number of shots necessary for bending without deformation of the pipe may be calculated. The number of shots are marked on the outer surface of the pipe with a pencil and it can be readily perceived that errors can very easv ilyoctzurduring such marking because of the fact that the shots are normally divided into thousandths of an inch. Because of this highly inaccurate procedure, it has been the usual practice heretofore to attempt to get the degree of bend with the required radius as close as possible ,and then cut off either one. or both ends of the pipe on each end of the bend so that the specified length 2,961,090 Patented Nov. 22, 1960 of pipe is obtained. This, of course, is extremely costly because of the conduit wastage and the fact that very often conduits must be discarded in their entirety because the bend was not of the proper degree with the required radius. The problem is further complicated by the fact that the bending must be carried out as fast as the workmen place the conduits in place and thus, the whole construction operation has been heretofore seriously impaired by the failure to provide a satisfactory method of bending electrical conduits at the same rate that the same may be mounted in position on the building.

It is, therefore, an important object of this invention to provide mechanism for advancing pipe through pipe bending apparatus in a manner so that the pipe is bent at a predetermined degree of bend, at a designated radius, and with the outer end of the pipe at a specified distance from the longitudinal length thereof remaining unbent without in any manner causing deformation or adverse effects on the pipe during such bending.

An equally important object of this invention is to provide precision pipe advancing mechanism for bending machines wherein the mechanism includes components for advancing the pipe through the bending apparatus at predetermined, exactly equal increments which are accurate to one thousandth of an inch.

Another important object of the instant invention is to provide precision pipe advancing mechanism as referred to above which includes shiftable structure for supporting a pipe to be bent in a position to be received.

within pipe bending apparatus and including power operated means releasably connected with the structure for intermittently shifting the latter and, thereby, the pipe toward the apparatus in predetermined increments accurate to very precise specifications, whereby the pipe may be bent at spaced intervals along the length thereof with a high degree of accuracy.

Also an important object of the invention is to provide power operated means for advancing the pipe sup porting structure as defined above and including an elongated screw coupled with an electrical motor having brake means as a part thereof, whereby the structure is shifted toward the pipe bending apparatus during operation of the motor but discontinues shifting movement toward the bending apparatus immediately upon deactivation of the motor to thereby assure shifting of the structure through accurate, predetermined increments. This arrangement prevents inadvertent shifting of the pipe carrying structure relative to the pipe bending apparatus during periods of inactivation of the advancing motor, inasmuch as the pipe supporting structure remains in releasable engagement with the power screw at all times regardless of the condition of operation of the advancing motor.

Other important objects of this invention relate to the provision of pipe advancing mechanism wherein is included an elongated track shiftably supporting a pipe carriage, and with the screw connected to the power motor and disposed in parallel relationship to the track being capable of reciprocating to a limited extent relative to the motor and thereby the track to permit the carriage to shift during actual bending of the pipe and thus eliminating stresses and strains on parts of the pipe advancing mechanism which would otherwise occur if the pipe were held in a stationary position as the same was bent by I the shoe forming a part of the bending apparatus; to the to insure subsequent advancement of the pipe an exact preselected distance; to the provision of mechanism as described wherein the motor coupled with the screw for advancing the pipe supporting carriage is reversible to permit power return of the carriage to the end of its path of travel remote from the bending apparatus, whereby the operator may effect return of the machine to its initial operating position while marking another pipe to be bent and thus effecting a considerable saving iii-time required to bend a large number of pipes; and to other important objects and details of construction which will become obvious or be explained more fully as the following specification progresses.

In the drawings:

Figure l is a plan view of a pipe bending machine having precision advancement mechanism thereon embodying the concepts of the present invention, certain parts thereof being broken away to reveal details of construction thereunder;

Fig. 2 is a side elevational view of the machine illustrated in Fig. l and showing the normal position of a pipe and the apparatus for bending the same in phantom;

Fig. 3 is a fragmentary, enlarged, plan view of the pipe carriage forming a part of the present advancing mechanism, with certain parts thereof being broken away to reveal details of construction;

Fig. 4 is a fragmentary, enlarged, vertical, crossseotional view taken on the broken line 4-4 of Fig. 3 and looking in the direction of the arrows; V Fig. 5 is a schematic diagram of the wiring circuit forming a part of the present mechanism; and

Fig. 6 is an enlarged, vertical, cross-sectional view taken on the line 66 of Fig. l.

A pipe bending machine broadly designated by the numeral 10 and including a frame 12 and pipe bending apparatus generally designated 14, embodies pipe advancement mechanism 16 constructed in accordance with the principles of the present invention and illustrated in the drawing in its preferred form. Frame 12 includes a substantially rectangular upper rack 18 normally supported in a horizontal position by lower structure 20 including upright legs 2-2 at each corner thereof having adjustable means 24 permitting the effective length of each leg 22 to be variedso that rack 18 may be positioned in a horizontal plane, regardless of the irregularity of the surface 2-6 upon which machine 10 is positioned.

Crossbars 28 carried by rack 13 support a rectangular track 30 which includes a pair of parallel, horizontally disposed rails 32 and 34 which extend the longitudinal length of rack 18 and are substantially coextensive in length therewith.

Means for supporting pipe bending apparatus 14 at one end of rack 18 includes a pair of spaced, upright mounting plates 36 supported in parallel relationship by a number of standards 38 secured to corresponding crossbars 28 and 40. Pipe bending apparatus 14 includes a pair of upright, horizontally spaced, triangular supports 42 pivotally mounted on plates 36 at corresponding apexes thereof and which serve as supports for a pair of opposed forming blocks 44 and hydraulically actuated means 46 provided with a vertically reciprocable shoe 48 disposed between blocks 44.

An elongated screw 50 is rotatably carried by spaced bearing means 52 and 53 respectively mounted on ends 54 and 55 respectively of track 30, with screw 50 being disposed in a horizontal plane parallel with rails 32 and 34 and medianly positioned between the latter. Bearing means 52 includes a bearing 57 slidably receiving the corresponding, non-threaded end of screw 50, with collars 5 1 and 59 releasably secured to the non-threaded proximal end of screw 50 being disposed in spaced relationship and on opposite sides of bearing 57 in order to limit reciprocation of screw 50 relative thereto. Coil spring 63 surrounding the non-threaded end of screw 50 and interposed between collar 51 and bearing 57 normally biases screw 50 away from pipe bending apparatus 14.

A prime mover 56 in the nature of an electric motor having a magnetic clutch associated therewith, is mounted of; rack 18 at the end thereof opposed to bending ap i paratus 14 and is operably coupled to a flexible coupling broadly numerated 60 through an intermediate gear reducer 58.

Bearing means 53 includes a bearing 65, mounted on the upper surface of end 55 of track 30 slidably receiving the proximal non-threaded end of screw 50, with collar 67 secured to screw 50 inwardly of bearing 65 serving to limit shifting movement of screw 50 toward flexible coupling 60. The inner hub 69 of coupling 68 mounts a sleeve 71 which has internal, longitudinally extending grooves 73 therein adapted to comp-lementally receive the proximal splined end of screw 50, whereby the latter is permitted to shift relative tocoupling 60 while driving interengagement therebetween is maintained.

Advancement mechanism 16 shiftably mounted on track 30 includes a carriage designated 61 provided with a rectangular, horizontally disposed plate 62 overlying track 30 and screw 50 and having a pair of opposed sides 64 and 66 depending from the lower face thereof and disposed in parallel relationship to rails 32 and 34. A pair of rollers68 are rotatably mounted on each of the sides 64 and 66 adjacent the lower edge thereof and at opposed ends of the same and, as clearly illustrated in Fig. 4, rails 32 and 34 are substantially U-shaped in cross-section to present a pair of opposed legs 70 with rollers 68 being disposed between corresponding legs 70 of a respective rail 32 and 34. It can now be perceived that carriage 61 is shiftable along the longitudinal length of track 30 as rollers 68 rotate within corresponding rails 32 and 34 and support carriage '61. Structure 72 for holding a pipe 74 in a horizontal position to be received in pipe bending apparatus 14 is positioned on the uppermost face of plate 62 and includes a clamp 76 adapted for holding pipes or conduits 74 of various diameters in a horizontal position. Centering mechanism broadly nu-- merated 78 is also carried by the upper face of plate 62 for maintaining pipe 74 in longitudinal alignment .with rails 32 and 34 so that the same is directed into apparatus 14 in exact alignment with blocks 44. Centering mechanism 78 is provided with an elongated cross screw 80 rotatably mounted in spaced brackets 82 and 84 disposed on the upper face of plate 62 and rotatably receiving a pair of spaced, hexagonal collars 86, each having an upright pipe-engaging stop 88 on the upper face thereof. Screw 80 is threaded in different directions on opposite sides of bracket 82 so that as the same is rotated by turning handle 90, stops 8% are moved toward or away from each other depending upon the direction of rotation of screw 80, it being apparent that stops 88 cannot rotate with respect to screw 80 because of the interengagement of the lower flat faces of hexagonal collars 86 with the upper face of plate 62.

Means for operably interconnecting carriage 61 witb screw 59 includes a solenoid 92' and manually operable arm means broadly numerated 94, and both coupled to threaded means 96. As best shown in Fig. 4, threaded means 96 includes a half nut adapted to be moved into complementally threaded'engagement with screw 50 and an upright block 106, pivotally connected to the armature 97 of solenoid 92, with block 106 being connected to half nut 100 by a pair of vertically spaced connecting links 108 disposed on opposed sides of screw 50 and with each of the links being somewhat longer than the outer diameter of screw 50. Projection 102, rigidly secured'to the outer surface of half nut 100 and projecting in a direction away from screw 50, serves as means for mounting upright member 104 of arm means 94 and which in turn has an elongated section 105 secured to the upper. end thereof and extending outwardly of carriage 61' through slot 107 provided in side wall, 66. Inwardly extending notch 109 provided in section 105 is of a width to receive the lower edge portion of side wall 66 defining a part of slot 107, with notch 109 being positioned to maintain half nut.100 out of engagement with screw 50 when notch 109 receives. the defined edge of side wall 66.

A pair of horizontally spaced, substantially L-shaped mounts 110 and 112 are suitably secured to the outer face of side 64 by welding or the like and serve to mount locking means broadly designated by the numeral 114. As illustrated in Fig. 3, locking means 114 includes an elongated cylindrical rod 116 carried by mounts 110 and 112 and keyed to the latter adjacent the lowermost ends of the vertical portions of mounts 110 and 112 and parallel to and spaced from rail 34. An elongated sleeve 118 is slidably telescoped over and keyed to rod 116 for movement with respect thereto and has an elongated, irregularly shaped bracket 120 welded to the normally uppermost surface thereof, it being apparent from Fig. 3 that the outermost end of bracket 120 extends through an opening in side 64 into partial overlying relationship to the upper leg 70 of rail 34. An elongated element 122 is pivotally attached intermediate its ends to the lower face of bracket 120 adjacent the outer end of the latter. A pair of stops 124 and 126 are secured to the lower face of element 122', depend therefrom and are located on opposite sides of the point of pivotal interconnection of bracket '120 and element 122, it being noted that stop 124 is disposed on the inside of rail 34 while stop 126 is located on the outside thereof. A substantially L-shaped bracket 128 has a horizontal leg 130 welded to the surface of sleeve 118 away from carriage 61 and an upright leg 132 remote from sleeve 118. A solenoid 134 secured to leg 132 of bracket 128 has an armature 136 pivotally connected to the end of element 122 remote from stops 124 and 126 by a link 138, it being noted that the outer end of ,link 138 away from armature 136 is adjustably secured to element 122 by virtue of a screw 140 mounted on the outer end of element 122 and receiving the end of link 138. As shown in Fig. 3, an adjustable collar 142 is positioned over link 138 on each side of screw 140 so that the effective length of link 138 may be changed. Spring means (not shown) associated with solenoid 134 normally biases armature 136 toward the outermost end of its path of travel, while an elongated spring 146 suitably secured at one end thereof to mount 110 by a fastener 148 and to the end of leg 130 of' bracket 128 remote from leg 132 by a fastener 150 biases sleeve 118 and the parts mounted thereon toward mount 110 and thereby in a direction toward apparatus 14'.

A switch block 152 is secured to the upper face of leg 130 of bracket 128, extends upwardly therefrom and' terminates above the upper face of plate 62. As shown in Fig. 3, switch block 152 is spaced from and parallel" with side 64 and mounts a switch 154 extending through the same and having an actuating arm 156 projecting toward side 64.

Means for actuating switch arm 156 comprises an elongated cylinder 158 secured to a shaft 160 which is" threaded at one end thereof as at 162 and is rotatably' journalled in horizontally spaced bearings 164 and 166 welded to the outer face of side 64. A set collar 168 secured to the outer end of shaft 160 adjacent bearing 164 prevents relative movement of shaft 160 in a direction toward bearing 166, while micrometer means broadly designated by the numeral 170 isprovided adjacent bearing 166. Micrometer means 170 includes an annular member 172 secured to hearing 166 and re- 158 and extends upwardly a suflicient distance to engage arm 156 when switch 154 is moved to a position proxi-' rnal to stop 178. An adjustable stop in the nature ofv a horizontally disposed screw 179 rotatably threaded into the lower lateral leg of mount 110 serves'to'limit An elongated, upright stop" the extent of reciprocation of sleeve 118 toward mount 110. In this manner, the point at which stop 178 engages switch arm 156 to actuate switch 154 may be adjusted so that the zero numeral on the scale on member 172 moves into accurate alignment with the zero of the scale on member 174 exactly at the moment that switch 154 is actuated by stop 178.

' Machine 10 has electrical control means broadly designated by the numeral 180 for controlling operation of motor 56 and solenoids 92 and 134. A pair of power lines 182 and 184 forming a part of control means 180 are adapted to be connected to respective terminals which may be joined to a source of electrical power. Single pole, single throw, main power switch 186 interposed; in line 182 permits energization or deenergization of. the entire control circuit. Line 182 is connected. to the coil 188 of relay 220, while line 190 grounds coil 188 to line 184. A push button, normally two-point make switch 192 is positioned in line 182, while switch 154 is interposed in line 182 between switch 192 and coil} 188 of relay 220. Relay 220 has a pair of ganged pole pieces 194 and 196, with pole piece 194 being movable between 21 pair of contacts 198 and 200 while pole piece 196 is movable into and out of engagement with contact 202 in response to energization of relay 220. It is to be noted that during the period of deenergization of' coil 188, pole piece 194 is in engagement with con-- tact 198 While pole piece 196 is out of engagement with contact 262.

Line 204 interconnects contact 198 and the coil 206 forming a part of the brake of motor 56, while line 208 grounds coil 206 to line 184, the latter in turn being connected to the coil of solenoid 134.

Lead 210 joins pole piece 194 to power is joined to contact 222 by line 234. Windings 228 and 232 are grounded to line 184 by lead 236 having 7 limit switch 238 interposed therein and provided with I a'normally closedv switch. arm 240.

Line 242 couples line 212 to solenoid 92 and groundline 244 interconnects the 'coil of solenoid 92 with line v 184; Power'is provided to the coil of solenoid 134 by 50' a? line 246 joined to line 242.

In operation, the operator of machine 10 determines the number ofrshots necessary to bend a pipe 74 in the nature of an electrical conduit or the like in the desired degree of bend at the particular radius necessary and, with the uppermost end of the bent part of the pipe.

terminating at a predetermined distance with respect to the longitudinal unbent length of the pipe after the bending operation has been completed. As heretofore pointed out, movement of thepipe for. each shot most usually must be less than one and one-half inch to pre-- vent deformation of the pipe when shoe 48 contacts pipea; Therefore, the operator may 74 between blocks 44. readily calculate the increment of movement of the pipe for each shot in order to prevent damage to the pipe While at the same time obtaining the necessary bend in such pipe.

Knowing the exact distance which the pipe must move for each shot, the operator then turns handle means line 182. and. line 212 couples contact 200 to the pole piece 214m a single pole, double throw switch 216 having a pair of opposed contacts 218 and 222 which are alternately termined. Inasmuch as the calibrations on members 172 and 174 arein thousandths of an inch, it can be readily appreciated that the distance which it is desired to move pipe'74 foreach shot may be accurately set up on machine 10' by turning handle 176 and thereby member 174 a desired number of revolutions.

An elongated length of pipe 74 in the nature of an electrical conduit is positioned in clamp 76 so that the same extends longitudinally of rack 18 in parallelism with rails 32 and 34. Clamp 76 is brought into tight engagement with pipe 74 and then handle 90 is turned to rotate screw 80 in a direction to move stops 88 into engagement with pipe 74. It can be appreciated that since stops 88 are positioned in equally spaced relationship to bracket 82, upon engagement of both of the stops 88 with pipe 74, the latter is maintained in exact paralelism with rails 32 and 34.

Main switch 186 is closed to permit energization of the circuit illustrated in Fig. 5, whereupon the operator grasps the outer end of section 105 of arm means 94 and moves section 105 upwardly and inwardly until notch 109 clears the proximal edge of side wall 66 defining the lower part of slot 107. It is to be noted that upon closing of main switch 186, the coil 206 of the brake forming a part of motor 56 is energized through a circuit including power line 182, closed switch 186, lead 210, pole piece 194, contact 193, line 204, coil 206, line 208 and ground line 184. Apphcation of the brake of motor 56 prevents rotation of the shaft thereof until deenergization of coil 206. The windings 228 and 232 of motor'56 are maintained in a deenergized condition throughout the period of energization of coil 206 by virtue of pole piece 194 remaining out of engagement with contact 200 so.

long as the coil 188 of relay 220 remains deenergized. Switch 216 is closed by shifting arm 214 thereof into engagement with contact 218 which permits energization of motor 56 to shift carriage 61 toward pipe bending apparatus 14, and then the operator pushes inwardly on the normally open switch 192 to permit current to flow through a path traced by power line 182, closed switch 186, switch 192 held in a closed position, closed switch 154, the coil 138 of relay 220, line 190 and ground line 184. Energization of coil 1'88 shifts pole piece 196 ofrelay 220 into engagement with contact 202, while pole piece 194 is shifted out of engagement with contact 198 into engagement with contact 200. The coil 188 of relay 220 thereby remains energized even though switch 192 is permitted to open, by virtue of current passing through line 182, closed switch 186, lead 224, pole piece 196, contact 202, lead 226, line 182, closed switch 154, coil 188, line 190 and ground line 184. The coil 206 of the brake forming a part of motor 56 is deenergized by virtue of the shifting of pole piece 194 away from contact 198 and thereby breaking of the circuit to coil 206, while winding 228 of motor 56 is energized through line 182, closed switch 1.86, lead 210, pole piece 194, contact 200, line 212, pole piece 21 4, contact 218, line 230, winding :32, lead 236, closed limit switch 238 and ground line It is also to be noted that shifting of pole piece 194 into engagement with contact 200 causes solenoids '92 and 134 to be actuated by virtue of a circuit traced from contact 200 through line 212, line 242, the coil of solenoid 92 and ground line 244 coupled with line 184 as Well as the coil of solenoid 1 34 which is in parallel with solenoid 92 through line 246 connected to line 242 and ground line 184 connected to the coil of solenoid 134.

Energization of the coil of solenoid 92 retracts the armature 97 therein, thus shifting half nut 100 into complemental threaded engagement with screw 50, while energization of solenoid 134 causes the armature 136 to be retracted into the solenoid housing and effecting rotation of element 122 about the axis of pivotal mountingthereof oubrficket 120, whereby stops 124 and 126 are moved into binding engagement with rail 34 of track 30.

The link 138 interconnecting element 122 and armature 13,6 effects swinging of element 122 in response to reciprocation of armature 136, with adjustable collars 140 and :142 providing means for obtainingthe proper amount of pressure on element 122 and thereby the stops 124 and 126 in engagement with track 30.

Since motor 56 is energized to rotate screw 50 through gear box 58 and flexible coupling 60 in a direction to shift carriage 61 toward pipe bending apparatus -14, it can be seen that switch block 152 carried by sleeve 118 mounted on rod 116 remains in a tixed position relative to side-rail 34 of track 30, while cylinder 158 having upright stop 178 mounted thereon shifts toward switch arm 156 and in response to movement of carriage 61. When stop 178 engages switch arm 156, the latter is moved to an open position, thereby breaking the circuit to coil 1880f relay 220 and permitting pole piece 196 to move out of engagement with contact 202 and pole piece 194 to move into engagement with contact 198. This eifects breaking of the circuit to solenoids 92 and 34 While at the same time deactivating winding 228 of motor 56. Simultaneously therewith, coil 206 is energized upon closing of the switch provided by pole piece 194 and contact 198 of relay 220. Thus, upon opening of switch 156, rotation of screw 50 immediately ceases not only because of deenergization of the'winding 228 of motor 56 but also because of actuation of the coil 206 of the magnetic brake forming a part of motor 56.

Upon deenergization of the coil of solenoid 134, the armature 136 thereof is permitted to shift outwardly under the action of the spring within the housing of solenoid 134, whereby link 138 shifts-element 122 about the axis of pivotal mounting thereof on bracket 120 and thus moving stops 124 and 126 out of engagement with opposedsides of rail 34. The sleeve 118 carrying bracket 120 and thereby the locking means 114 is thus free to move toward pipe bending apparatus 14 under the influenceof spring 146 and until sleeve 118 engages screw 179; Movement of, sleeve 118 in a direction toward solenoid 134 also moves switch block 152 and switch 154 thereon away from stop 178 a distance determined by the position of screw 179 carried by mount 110. It is to be understood that half nut remains in engagement with screw 50 during this period, inasmuch as solenoid 92 does not include spring means for biasing the armature 97 thereof outwardly during the time that the coil of solenoid 92 is denergized. Since half nut 100 remains in engagement with screw 50, carriage 61 cannot move relative to the latter in the event the operator inadvertently engages carriage 61.

Pipe bending apparatus 14 is then actuated to move the shoe 48 thereof toward and into engagement with pipe 74 for bending the same to apredetermined arc; During bending of pipe 74 with shoe48, pipe 74 and carriage 61 carrying the same'areshiftable relative to track 30 by virtue of the slida ble interconnection of one end of screw 50 with flexible coupling 60, asdes'cribed above. This construction prevents deleterious stressesrand strains being imparted to screw 50 by virtueof the tendency of 'pipe 74 to move forwardly during bending thereof with shoe 48. When the desired arc has been imparted to pipe 74, the pressure is released on ram'46' causing shoe 48 to retract away from pipe 74 and thereby permitting the same as well as carriage 61 toreturn to the initial position thereof under the influence of spring means 63.

9 156 of switch 154 with stop 178 terminates movement of carriage 61 after movement thereof a predetermined distance.

The operator may return carriage 61 to the end of its path of travel adjacent motor 56 by shifting pole piece 214 into engagement with contact 222, whereby winding 232 is energized through power line 182, closed switch 186, lead 219, pole piece 194, contact 200, line 212, pole piece 214, contact 222, line 234, winding 232, lead 236, closed limit switch 238 and ground line 184. The operator may stop return carriage 61 at any desired point by opening switch 216, but if he inadvertently fails to perform such operation, movement of carriage 61 into engagement with switch arm 24!) of limit switch 238 breaks the circuit to Winding 232 and thereby stops motor 56 in conjunction with energization of magnetic brake coil 206.

If desired, solenoid 92 may be eliminated and arm means 94 employed to shift half nut 100 into and out of engagement with screw 54). In this event, another notch should be provided in section 105 of arm means 94 in a position to receive the lower margin of wall 66 defining a part of slot 107, when half nut 100 is in firm complemental threaded engagement with screw 50.

It should be emphasized that the operator of machine may quickly place the desired bend in a pipe 74 by merely calculating the distance which pipe 74 should be moved for each shot and then setting up such distance by rotating member 174 of micrometer 170 the desired amount to move stop 178 away from switch arm 156 the requisite distance. Then, the entire bending operation may be carried out by merely closing switch 192 when desired to effect forward movement of carriage 61, with movement of the latter being automatically stopped by opening of switch 156.

One important feature of the invention is the fact that intermittent shifting of carriage 61 toward bending apparatus 14 is entirely at the control of the operator so that the bending of pipe 74 may be closely controlled. Furthermore, this permits the operator to unclamp pipe 74 from structure 72 so that the pipe 74 may be rotated about its longitudinal axis a certain degree, to the end that three-dimensional curves may be readily formed in pipe 74 if desired.

Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is:

1. In pipe advancing mechanism for a machine provided with pipe bending apparatus, shiftable structure adapted to support a length of pipe in a position to he received by said apparatus; an elongated track; a carriage shiftably supported on the track with said pipe disposed in a position to be received by said apparatus; power operated means releasably coupled with said carriage for shifting the latter toward the apparatus; structure shiftably carried by the carriage and including lock means releasably cngageable with said track whereby the carriage shifts relative to said lock means when the latter is engaged with said track; means for selectively actuating the power means to shift the carriage toward said apparatus and relative to said lock means engaged with the track; and precision control means for deactivating said power means and thereby effecting stopping of movement of said carriage after the latter has shifted a preselected distance from said locking means engaging the track.

2. Pipe advancing mechanism as set forth in claim 1 wherein said precision control means includes selective deactuating means for selective deactivation of said power operated means after the carriage has shifted relative to said locking means any one of a substantially infinte number of distances with a predetermined range.

3. Pipe advancing mechanism as set forth in claim 1 wherein said power operated means includes an electric motor having an output shaft, means releasably coupling said shaft with said carriage for shifting the latter toward the apparatus during activation of the motor, and brake means associated with said motor for substantially immediately stopping rotation of said shaft upon deactivation of said motor after operation thereof.

4. Pipe advancing mechanism as set forth in claim 3 wherein said means releasably coupling said shaft to the carriage includes an elongated screw connected to said shaft, rotatable therewith and parallel with said track, and threaded means carried by said carriage and movable into and out of complemental threaded engagement with the screw.

5. Pipe advancing mechanism as set forth in claim 4 wherein is provided means interconnecting the screw and the shaft and including components permitting limited longitudinal reciprocation of the screw relative to said shaft and while continuing to be driven thereby.

6. Pipe advancing mechanism as set forth in claim 5 wherein is provided spring means connected to said screw for biasing the latter toward said shaft of the motor.

7. Pipe advancing mechanism as set forth in claim 4 wherein is provided solenoid means coupled with said threaded means for shifting the latter into complemental threaded engagement with the screw upon energization of said solenoid means.

8. Pipe advancing mechanism as set forth in claim 7 wherein is provided manually operable arm means coupled with said threaded means for shifting the latter out of engagement with said screw.

9. Pipe advancing mechanism as set forth in claim 8 wherein said arm means have an outer elongated section and said carriage includes a side wall having a slot therein for clearing the outer, elongated section of said arm means, said section being provided with a notch therein disposed to selectively receive one edge of the side wall defining said slot therein, said notch being positioned to maintain said threaded means out of engagement with the screw when the notch receives said edge of the side wall.

10. Pipe advancing mechanism as set forth in claim 3 wherein said motor is reversible for shifting the carriage toward the motor and away from said apparatus when the motor is operated to rotate said shaft in one direction thereof, there being limit switch means interposed in the path of travel of the carriage for deactivating the motor when the carriage has moved into a predetermined location proximal to the shaft of said motor.

References Cited in the file of this patent UNITED STATES PATENTS 1,587,158 Husid June 1, 1926 

